Linux – How to open a file read-only from command line with emacs/vi/vim

1. You've got this handled

2. Yes, you'll want to use emacsclient. To get a new frame, add the -c option. I have an alias to make it quicker and to tell emacsclient not to wait for emacs server to return:

   alias em='emacsclient -n'
   

3. emacsclient -nw
4. I'm not sure about this. I start Emacs once and always load new files either within emacs or using my em alias.

Update:

Check out this tip documenting how to use Platypus to create an app wrapper around emacsclient. You could then use "Open With..." to launch using your new app wrapper.

what you are looking for is emacs server mode. Add this line to your .emacs file:

(server-start)

Then, open the file using emacsclient:

emacsclient foobar.txt

Have a look at this page for more information.

To avoid having to start emacs manually or setting it to auto-start, you could write a little function that tries connecting to a running server (by running emacsclient) and if not, runs emacs instead. Add this to your shell's configuration file (e.g. ~/.bashrc):

emacs(){ 
    emacsclient "$@" 2>/dev/null || /usr/bin/emacs "$@" 
}

Now, simply running emacs file will either start the server or connect to an existing instance.